liebert® crv™ application guide - vertiv.com

Liebert® CRV™

Air-Cooled, Water/Glycol-Cooled and Chilled Water,50 & 60Hz

Application Guide

Technical Support Site

If you encounter any installation or operational issues with your product, check the pertinent section ofthis manual to see if the issue can be resolved by following outlined procedures. Visithttps://www.VertivCo.com/en-us/support/ for additional assistance.

TABLE OF CONTENTS

1 What is the Liebert CRV? 5

1.1 Liebert CRV Intended Application 5

2 Liebert CRV Controls 7

2.1 Liebert CRV Sensor Location Guidelines 8

3 General Liebert CRV Guidelines 9

4 Site Application and Unit Placement 11

Vertiv | Liebert®CRV™Application Guide | 3

1 WHAT IS THE LIEBERT CRV?The Liebert CRV is a Precision Cooling unit intended to be located within a row of heat-generating ITequipment racks. The Liebert CRV provides all the necessary functions of a precision air conditionerincluding cooling, humidification, dehumidification, air filtration and condensate management. Air entersthe Liebert CRV unit from the hot aisle. The air, filtered, cooled and conditioned, is discharged into thecold aisle through an adjustable supply air baffle. The supply air baffle allows the air leaving the coolingunit to be directed to the racks the Liebert CRV is conditioning; maximizing its effectiveness, reducing thechance for hot spots and improving the overall system efficiency.

The Liebert CRV is optimized for maximum cooling capacity in a minimal footprint. The extremely energyefficient components of the system are managed by the Liebert iCOM control system. The environment ismonitored in real time by the Liebert iCOM control through sensors positioned in a variety of locations.Sensors located in the return air, supply air and rack inlets allow the unit to optimize its operations forboth performance and energy efficiency. All unit operations and sensor data can be reported remotely viaa variety of communication protocols, providing end users with a built-in mini-monitoring system.

1.1 Liebert CRV Intended Application

The Liebert CRV can be utilized in a variety of applications. Since the Liebert CRV provides completetemperature and humidity control along with filtration, it can be deployed as the only cooling unit in smalldata centers and network closets. Larger data centers are able to benefit from its standard rack-sizedfootprint, deploying it as a supplemental spot cooler to address both hot spots and high-density racks.The small footprint and variable cooling and airflow allow the Liebert CRV to be initially oversized inanticipation of future IT expansion without any footprint or energy consumption penalties. The LiebertCRV can be applied on both raised and non-raised floors, allowing it work with existing under floor andoverhead cooling systems. The Liebert CRV can operate in conjunction with an existing Liebert XDinstallation, or provide an excellent alternative for sites that are unable to support a Liebert XD system.The Liebert CRV is compatible with all types of aisle containment designs; however the Liebert CRVcontrol algorithms have been optimized for cold-aisle containment.


Figure 1.1 Liebert CRV—front and rear views


2 LIEBERT CRV CONTROLSThe Liebert CRV is equipped with the latest in Liebert iCOM controls. Available in every Liebert CRV is areturn temperature and humidity sensor, a supply temperature sensor and three remote rack sensorswith the option to add an additional seven remote rack sensors. Each rack sensor takes two temperaturereadings and can be configured to report either the average or the higher of the two sensors.

The Liebert iCOM controller on the Liebert CRV leaves the factory with the fan speed and coolingcapacity controlled by the supply air sensor. This control mode is extremely robust and will ensuredelivery of precise cooling to the cold aisle. To unlock the full capability of the Liebert CRV, remote racksensors can be installed, which will allow the fan speed and the cooling capacity to be “decoupled.”Decoupling means that the fan speed can now be controlled from the remote rack sensors and thecooling capacity controlled from the supply air sensor. In this advanced configuration, the Liebert CRVcan now control the discharge temperature of the unit by modulating cooling capacity based on thesupply sensor and use the remote rack sensors to ensure that the cool air is being delivered to the inlet ofthe racks. Using the supply and remote rack sensors in this decoupled mode is the preferred method forcontrolling the Liebert CRV in a hot-aisle/cold-aisle configuration. In addition to this configuration theLiebert CRV has additional flexibility for other applications that can be understood in Table 2.1 below.

Cooling Capacity

SupplyAir Sensor

RemoteAir Sensor

ReturnAir Sensor

Fan Speed

Supply Air Sensor A (Coupled) — —

Remote Air Sensor D (Decoupled) B (Coupled) —

Return Air Sensor E (Decoupled) F (Decoupled) C (Coupled)

Table 2.1 Coupled and decoupled control schemes

Table 2.1 above shows the flexibility of the Liebert CRV and how different sensor locations can be used tocontrol the Liebert CRV fan speed and cooling capacity. The configurations labeled “A,” “B” and “C” aredefined as coupled control schemes. These coupled control schemes allow both the cooling and fan speedto be controlled by the same sensor input, either from the supply air sensor, remote air sensor or return airsensor. Schemes labeled “D,” “E” and “F” are defined as decoupled control schemes. These decoupledcontrol schemes use separate sensor inputs for controlling the fan speed and cooling. For instance, analternate to the factory default control program is “D,” where the fans are controlled by the remote rack-mounted temperature sensors and the cooling is controlled by the discharge air temperature sensor inthe Liebert CRV.


2.1 Liebert CRV Sensor Location Guidelines

Three rack sensors come with the Liebert CRV unit to help prevent any problem spots in the row. Racksensors help combat cooling problems related to recirculation of air, uneven rack loading and airdistribution. The rack sensors are intended for use in the cold aisle only. To ensure effective coolingprovided by a Liebert CRV, follow these suggestions for locating the rack sensor probes:

• Place on the top of the perforated rack door.

• In front of the highest-mounted servers in the rack.

• In front of the highest-density area of the rack.

• In the airflow path entering the rack.

• Do not place the probe directly on the metal surface of the perforated door.

Additional information about sensor location can be found in the Liebert CRV Installation, Operation andMaintenance manual, SL-11975, which is available at www.VertivCo.com.


3 GENERAL LIEBERT CRV GUIDELINESThe Liebert CRV is capable of supporting many varied room configurations. Following a few basicguidelines, the Liebert CRV can provide efficient and precision cooling to the space and adjacent rackmounted equipment. The following points are highly effective recommendations for precisionperformance and efficient operation of the Liebert CRV in many room layouts:

• Distribute equipment as evenly as possible across the height of the rack.

• Use blanking panels to prevent recirculation of air through gaps in rack equipment.

• Locate racks closely together, preventing gaps between equipment racks.

• Where applicable, use dividers to prevent hot air wrap around to the cold aisle.

• Locate the Liebert CRV appropriately to effectively deliver cooling to the rack row.

The application of a Liebert CRV is meant to provide cooling to between two and six racks of equipment ina single row. A row of equipment longer than six racks might not receive the appropriate quantity ofconditioned air from a single Liebert CRV unit. The total number of racks that can be cooled will dependfully upon the rack loads and airflow requirements of the equipment to be cooled, as well as the type andsize of the Liebert CRV selected. In conjunction with Liebert CRV placement, maintaining a cold aislebetween three and four feet wide is highly suggested. This is beneficial because it provides a smallervolume for conditioned air to inhabit, preventing hot aisle air intrusion. The density of the conditioned airwill help to prevent hot aisle air from recirculating through the rack equipment. Wider cold aisles can beutilized with cold aisle containment designs, including the Liebert Cold Aisle Containment product line.



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4 SITE APPLICATION AND UNIT PLACEMENT

Scenario 1: Single Equipment Row

The Liebert CRV is intended to cool a single row of racks by providing a curtain of cold discharge airacross the face of the equipment. Ideally the Liebert CRV should be located at the end of the rack rowwith a three to four foot cold aisle. Adjustment to the baffle system will allow cooling to be directed downthe row effectively delivering coverage to the rack row.

NOTE: It is not ideal to place the Liebert CRV in the middle of a single rack row. Middle placement maycreate hot spots at the top of the rack equipment, due to inconsistent air coverage.


Scenario 2: Double Equipment Row

When using a Liebert CRV with double rack rows, location of the Liebert CRV unit is similar to the single-row placement. Locate the Liebert CRVs at opposite ends of the two rows and adjust the air baffles in thedirection of desired cooling. Placing the Liebert CRV at opposite ends of each row will allow the LiebertCRVs to provide coverage for both rack rows by pressurizing the cold aisle. Increased pressurization in thecold aisle helps to eliminate any hot spots from developing in the row. Double-row usage simulates acontainment approach. The opposing rack row acts as a wall or partition, helping to contain the providedcooling in the cold aisle instead of allowing it to spread throughout the space that the equipment islocated.

NOTE: It is not suggested to locate two Liebert CRV units directly across from one another or bylocating two units adjacent to one another in a row. Both situations have potential to reduce theeffective cooling of both Liebert CRV units in the row. If more than one Liebert CRV unit needs to beplaced within a row, separation of at least one rack is recommended.


Scenario 3: Redundancy

Single-Row Redundancy

Single-row redundancy can be achieved by locating two Liebert CRV units at opposite ends of a row, asshown. Directing the air baffles toward one another and down the face of the rack row will allow the LiebertCRV units to operate at partial load while providing the required cooling. If a unit failure should occur, theremaining unit will ramp up airflow, respond to the higher return air temperature and provide the requiredcooling based on input from sensor data. This scenario can also work in a lead/lag operation or duty cyclescenario, by running a single Liebert CRV to match the load with the secondary unit in standby. Two ormore Liebert CRVs can be networked together for teamwork, lead/lag or cascade operation.


Dual-Row Redundancy

Dual-row redundancy can be achieved in a similar manner to a single row redundancy plan. In thisscenario, two single rows are facing one another, sharing a cold aisle. Liebert CRV units may be networkedtogether to provide shared informed coverage of the row equipment demands. Redundancy can beaccomplished by locating Liebert CRVs at the ends of the rows and directing their airflow inward towardsthe equipment row, as shown. Operating all four Liebert CRV units at partial load or two units at full loadwith two in standby is recommended for unit redundancy. Furthermore, it is suggested that when utilizingthis configuration, Liebert CRVs at opposite ends of the rows should be in operation, to deliver the mosteffective coverage to the equipment. Aligning two Liebert CRVs across the row from one another is anacceptable design, assuming that each Liebert CRV will be operating at partial capacity or operatingtogether at full capacity only in an emergency situation.

NOTE: Equipment loads that require a greater amount of cooling can utilize additional Liebert CRVslocated in-between the row of equipment. The discharge of the in-between Liebert CRVs should bedirected both to the left and right, adding supplemental cooling to the effect of the Liebert CRVslocated at the end of the row.


Scenario 4: Partial Containment

The Liebert CRV is most effective when the cold aisle can be contained by a natural or manufacturedobstruction opposite to the face of the unit. As can be seen in this layout, a single Liebert CRV ispositioned at the end of a rack row that is parallel to a room wall. The wall opposing the row equipmentacts as a containment barrier supporting pressurization of the cold aisle. Additionally, the end of theequipment row being located on a room wall acts as an end panel preventing wraparound of cool mixingwith the hot aisle air. In conjunction with this effect, the Liebert CRV discharge is positioned to provide acurtain of cooling that encapsulates the cold aisle, acting as an end cap to the cold aisle.

NOTE: To achieve a level of redundancy in this scenario, it is suggested to locate an additional LiebertCRV in one of two locations. Locate an additional operating Liebert CRV at the end of the equipmentrow adjacent to the wall (to the far left in the illustration above). The two units will operate at a reducedcapacity each, while still providing the required cooling. Should a failure of a unit occur, the remainingLiebert CRV unit will be able to provide cooling and airflow requirements from an acceptable position.Alternatively, locate a standby, non-operating Liebert CRV adjacent to the operating Liebert CRV. Thisallows for the same basic positioning of the unit while maintaining the intent of this scenario.


Scenario 5: Cold-Aisle Containment

The Liebert CRV is ideal for use with a cold-aisle containment approach, with the Liebert Cold AisleContainment solution or similar products. Utilizing the Liebert CRV in conjunction with cold-aislecontainment products does not limit the location of the Liebert CRV with respect to the rack row. TheLiebert CRV can be located anywhere within the equipment row, with the unit’s discharge air baffledirected as the equipment airflow needs demand. The cold aisle containment completely encapsulatesthe available cooling in the aisle maximizing cooling efficiency while preventing hot air intrusion through,around or over the row of equipment.


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© 2017VertivCo. All rights reserved. Vertiv and the Vertiv logo are trademarks or registered trademarks of VertivCo. All other names and logos referred toare trade names, trademarks or registered trademarks of their respective owners. While everyprecaution has been taken to ensure accuracyandcompleteness herein, VertivCo. assumes no responsibility, and disclaims all liability, for damages resulting from use of this information or for anyerrors oromissions. Specifications are subject to change without notice.

SL-11979_REV2_11-17/590-1785-501A

liebert® crv™ application guide - vertiv.com

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